1. Field of the Invention
The present invention relates to an inhibitor for the adhesion of lymphocytes to glandular cells which causes autoimmune adenitis such as that in Sjogren's syndrome.
2. Description of the Related Art
In general, immunocytes play an important role in protecting self systems from the invasion of foreign substances, etc. That is, with an invasion of foreign substances such as microorganisms, immunocytes such as T lymphocytes recognize these foreign substances and produce appropriate cytokines. Cytokines thus produced activate specific T cells. These activated T cells secrete cytotoxic substances to destroy the foreign substances and eliminate them from the inside of body. Thus, immunocytes distinguish between self systems and non-self foreign substances to destroy only the latter. This ability to distinguish between self system from non-self foreign substance is mainly based on the structure of proteins, etc. on the cell surface.
Although immunocytes primarily distinguish self from non-self and destroy only non-self, recently it has become evident that these immunocytes for unaccountable reasons erroneously recognize self system as foreign substance and destroy the self system, causing various disorders (autoimmune diseases).
For example, one of these autoimmune diseases is Sjogren's syndrome. As symtoms of this syndrome include symptoms such as dry eye due to alacrima, sialaporia, etc., manifestation due to some gland abnormality has been indicated to stimulate investigation along that line. As a result, it has become evident that Sjogren's syndrome is manifested by the destruction of secretory glands such as lacrimal and salivary glands by self immunocytes.
Although in Sjogren's syndrome the target self system of self immunocytes is evidently secretory glands such as lacrimatory gland, salivary gland, etc., the action mechanism of destroying target cells, that is, how immunocytes recognize, bind and destroy these target cells has not been ascertained.
On the other hand, the adhesion factor of immunocytes, more specifically that of lymphocytes involved in binding to intestinal epithelial cells, has been discovered [see The Journal of Immunology, 150, 3459-3470 (1993)]. Furthermore, the ligand of that adhesion factor has been identified as E-cadherin expressed on the epithelial cells of small intestine (Nature, 372: 190-193, 1994).
In view of these situation, the present inventors carefully studied to ascertain adhesion factors of glandular cells and immunocytes, and, based on each adhesion factor herein discovered, developed adhesion inhibitors which suppress the binding between these adhesion factors.